Due to the above problems, in recent years, there have been disclosed various methods of treatment without an operation. One of them is an artificial blood stent using a superelastic shape memory alloy wire.
As shown in FIG. 1, such an artificial blood stent 1 has such a shape that a hollow cylindrical connector, prepared to have a plurality of spaces and a predetermined length by weaving superelastic shape memory alloy wires, is attached to both sides of a main body made of fabric.
In addition to the artificial blood stent 1 illustrated in FIG. 1, various types of artificial blood stents 1 are recently utilized.
Such an artificial blood stent 1 is inserted into a lesion in a blood vessel by a separate insertion device, with its volume contracted to the minimum, and thereafter blocks an aneurysm region (swollen part) as it returns to its expanded shape, thereby preventing the risk of rupture due to a blood pressure.
Typically, an artificial blood stent insertion device comprises a moving tube 3 with a grip 8 fixed to one end inserted and placed into an outer tube 2 in front of a connector 7 so as to be movable back and forth, a guide passing tube 4 inserted and placed into the moving tube 3 for guiding a guide wire, and a cylindrical artificial blood stent 1 with a minimized diameter inserted between the moving tube 3 and the outer tube 2 and then placed into a blood vessel by pushing the moving tube 3 into the outer tube 2.
However, in case of using the aforementioned conventional device, the artificial blood stent 1 reassumes its expanded shape in the blood vessel by its elasticity the instant it is released from the insertion device. Due to this, in case of a high blood pressure, the artificial blood stent 1 is pushed down the blood vessel by the resistance caused by the flow of blood, thus it becomes difficult to accurately place the artificial blood stent 1 at a desired position in a blood vessel.
Due to these problems, a patent has to take antihypertensive agents in order to lower the blood pressure of the patient prior to an operation, and consequently the treatment costs increase and the risk of medical accidents become higher.
To overcome the above-described conventional problems, Korean Patent Laid-Open No. 2001-18324 proposes an artificial blood stent insertion device, which, in a case where the placement position of the artificial blood stent is wrongly selected due to the rear end of the stent woven into a wire, is capable of resetting a placement position after returning the artificial blood stent to its original position in the inside of the outer tube by pulling the stent along with an insertion tube.
However, the above insertion device still has the problem that the front end portion of the artificial blood stent being pushed out of the insertion device is immediately extended and grown when placing the artificial blood stent 1 in a blood vessel, and thus the artificial blood stent 1 is pushed down the blood vessel by being pushed by the flow of blood in the blood vessel.
To overcome the above-mentioned problem, Korean Utility Model Registration No. 20-0312490 proposes an artificial blood stent insertion device, as shown in FIG. 5, in which a wire hole 4′c is formed on the front end portion of a connecting tube 4′ to insert one end of a fixing wire 6 therein in a loop 6b shape, a core 5 projected to extend from the inside of the connecting tube 4′ to the outside of a grip 8 is inserted into the loop 6b of the fixing wire 6 for supporting it, and the other end of the fixing wire 6 is tied in a manner to surround only the front end portion of stent 1.
FIG. 5 is a cross sectional view showing the front end portion of the artificial blood stent 1 fixed by the core 5 by being tied into a contracted state by the fixing wire 6 in the artificial blood stent insertion device disclosed in the above Utility Model Registration No. 20-0312490.
However, the insertion device is disadvantageous in that the preparation for an operation is complex because it is necessary to make a knot 6c by tying the front end portion of the artificial blood stent 1 with the fixing wire 6, and when the stent is released from the outer tube, though the front end portion of the stent 1 is not immediately expanded, the middle portion and rear end portion of the stent 1 are immediately expanded and grown by its elasticity.
Due to this, the phenomenon that the stent 1 is pushed down the blood vessel by the resistance caused by the flow of blood in the blood vessel still occurs, thereby making it difficult to place the stent 1 at a desired position in a blood vessel.
Additionally, the above-described insertion device has a problem that the middle portion and rear end portion of the stent released from the outer tube is immediately expanded and grown and comes into contact with the walls of adjacent blood vessels even before removing the core 5, which makes it very difficult to find a desired vascular position and place and fix the artificial blood stent after extracting the artificial blood stent from the outer tube.